How to extract multiple day and time from a string in Kotlin-CodePudding

Hi I am developing an app using Kotlin that displays the operating hours of a mini mart. I am currently trying to reformat a given string of operating time of a mini mart so that I can display it in a string based on the mini mart's daily operating hours (I am reading from an API). The strings I am given are for example,

val string1 = "Mon-Thu, Sun 11:30 am - 9:00 pm  / Fri-Sat 11:30 am - 9:30 pm"
val string2 = "Mon-Sun 11:00 am - 10:30 pm" 
val string3 = "Mon-Thu, Sun 11:30 am - 10:00 pm  / Fri-Sat 11:30 am - 10:30 pm"

and I want to make them into a single string like

Mon 11:30 am - 9:00 pm  
Tue 11:30 am - 9:00 pm  
Wed 11:30 am - 9:00 pm 
Thu 11:30 am - 9:00 pm  
Fri 11:30 am - 9:30 pm  
Sat 11:30 am - 9:30 pm 
Sun 11:30 am - 9:00 pm

I appreciate your time to look into my problem.

CodePudding user response：

This function first creates a list of periods containing all possible combinations, like Mon-Tue, Mon-Wed, Mon-Thu, ..., Fri-Sat, Fri-Sun, Sat-Sun. The seven days are then appended to that list.

The main code works like this for this initial string:

Mon-Thu, Sun 11:30 am - 9:30 pm / Fri-Sat 11:30 am - 9:30 pm

Split string by "/"

Mon-Thu, Sun 11:30 am - 9:30 pm
Fri-Sat 11:30 am - 9:30 pm
For each item split by the first digit found (and trim)

parts[0]: Mon-Thu, Sun
parts[1]: 11:30 am - 9:30 pm
For each parts[0] split by comma to get the periods (and trim)

Mon-Thu
Sun
For each period filter periods and return the list with all days of that period

[ Mon, Tue, Wed, Thu ]
Return pairs with the index of the day within the week and the output string

1 to "Mon 11:30 am - 9:30 pm"
2 to "Tue 11:30 am - 9:30 pm"
3 to "Wed 11:30 am - 9:30 pm"
4 to "Thu 11:30 am - 9:30 pm"
Sort the result list by the index of the day within the week
Return the list joined by newlines

fun convert(s: String): String {
  val days = listOf("Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun")
  val periods = days
    .flatMap { from ->
      days
        .subList(days.indexOf(from)   1, days.count())
        .map { till -> "$from-$till" to days.subList(days.indexOf(from), days.indexOf(till)   1) }
    }   days.map { it to listOf(it) }
  return s
    .split("/")
    .flatMap {
      val parts = it.split("(?=\\d)".toRegex(), 2).map { s -> s.trim() }
      parts[0]
        .split(",")
        .map { period -> period.trim() }
        .flatMap { period ->
          periods
            .first { p -> p.first == period }
            .second
            .map { day -> days.indexOf(day) to "$day ${parts[1]}" }
        }
    }
    .sortedBy { it.first }
    .joinToString("\n") { it.second }
}

val string1 = "Mon-Thu, Sun 11:30 am - 9:30 pm  / Fri-Sat 11:30 am - 9:30 pm"
val string2 = "Mon-Sun 11:00 am - 10:30 pm"
val string3 = "Mon-Thu, Sun 11:30 am - 10:00 pm  / Fri-Sat 11:30 am - 10:30 pm"
val string4 = "Wed 9:30 am - 9:30 pm / Thu 10:00 am - 7:30 pm / Fri-Sat 11:30 am - 10:30 pm"
val string5 = "Fri 12:30 am - 7:30 pm"

println(convert(string1)   "\n")
println(convert(string2)   "\n")
println(convert(string3)   "\n")
println(convert(string4)   "\n")
println(convert(string5)   "\n")

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